如何删除此代码中ES6箭头函数的使用

我不熟悉ES6 arrow功能,我从供应商那里收到以下代码:

Highcharts.seriesType('linearregression', 'pareto', {
  name: 'Linear Regression'
}, {
  setDerivedData: function() {
    if (this.baseSeries.yData.length > 1) {
      var xValues = this.baseSeries.xData,
        yData = this.baseSeries.yData,
        mainData = this.baseSeries.data;
      var sum = [0, 0, 0, 0, 0],
        len = xValues.length,
        data, rise, gradient, intercept;
      Highcharts.each(xValues, function(x, i) {
        sum[0] += x;
        sum[1] += yData[i];
        sum[2] += x * x;
        sum[3] += x * yData[i];
        sum[4] += yData[i] * yData[i];
      });
      run = ((len * sum[2]) - (sum[0] * sum[0]));
      rise = ((len * sum[3]) - (sum[0] * sum[1]));
      gradient = run === 0 ? 0 : (rise / run);
      intercept = (sum[1] / len) - ((gradient * sum[0]) / len);
      function round(value, decimals) {
        return Number(Math.round(value + 'e' + decimals) + 'e-' + decimals);
      };
      function predict(x) {
        return [mainData[x].name, round((gradient * x) + intercept, 5)];
      };
      points = xValues.map(p => predict(p));
      this.setData(points, false);
    }
  }
});

我今天想把它投入生产,但刚发现IE中不支持ES6。如何重写它以删除箭头功能(下面的一行)?

      points = xValues.map(p => predict(p));